ordigi/elodie/geolocation.py

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"""Look up geolocation information for media objects."""
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from os import path
from ConfigParser import ConfigParser
import fractions
import pyexiv2
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import requests
import urllib
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from elodie import constants
from elodie.localstorage import Db
class Fraction(fractions.Fraction):
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"""Only create Fractions from floats.
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Should be compatible with Python 2.6, though untested.
>>> Fraction(0.3)
Fraction(3, 10)
>>> Fraction(1.1)
Fraction(11, 10)
"""
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def __new__(cls, value, ignore=None):
return fractions.Fraction.from_float(value).limit_denominator(99999)
def coordinates_by_name(name):
# Try to get cached location first
db = Db()
cached_coordinates = db.get_location_coordinates(name)
if(cached_coordinates is not None):
return {
'latitude': cached_coordinates[0],
'longitude': cached_coordinates[1]
}
# If the name is not cached then we go ahead with an API lookup
geolocation_info = lookup(name)
if(geolocation_info is not None):
if(
'results' in geolocation_info and
len(geolocation_info['results']) != 0 and
'locations' in geolocation_info['results'][0] and
len(geolocation_info['results'][0]['locations']) != 0
):
# By default we use the first entry unless we find one with
# geocodeQuality=city.
geolocation_result = geolocation_info['results'][0]
use_location = geolocation_result['locations'][0]['latLng']
# Loop over the locations to see if we come accross a
# geocodeQuality=city.
# If we find a city we set that to the use_location and break
for location in geolocation_result['locations']:
if(
'latLng' in location and
'lat' in location['latLng'] and
'lng' in location['latLng'] and
location['geocodeQuality'].lower() == 'city'
):
use_location = location['latLng']
break
return {
'latitude': use_location['lat'],
'longitude': use_location['lng']
}
return None
def decimal_to_dms(decimal, signed=True):
# if decimal is negative we need to make the degrees and minutes
# negative also
sign = 1
if(decimal < 0):
sign = -1
# http://anothergisblog.blogspot.com/2011/11/convert-decimal-degree-to-degrees.html # noqa
degrees = int(decimal)
subminutes = abs((decimal - int(decimal)) * 60)
minutes = int(subminutes) * sign
subseconds = abs((subminutes - int(subminutes)) * 60) * sign
subseconds_fraction = Fraction(subseconds)
if(signed is False):
degrees = abs(degrees)
minutes = abs(minutes)
subseconds_fraction = Fraction(abs(subseconds))
return (
pyexiv2.Rational(degrees, 1),
pyexiv2.Rational(minutes, 1),
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pyexiv2.Rational(
subseconds_fraction.numerator,
subseconds_fraction.denominator
)
)
def dms_to_decimal(degrees, minutes, seconds, direction=' '):
sign = 1
if(direction[0] in 'NEne'):
sign = -1
return (
float(degrees) + float(minutes) / 60 + float(seconds) / 3600
) * sign
def get_key():
config_file = '%s/config.ini' % constants.application_directory
if not path.exists(config_file):
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return None
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config = ConfigParser()
config.read(config_file)
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if('MapQuest' not in config.sections()):
return None
return config.get('MapQuest', 'key')
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def place_name(lat, lon):
# Try to get cached location first
db = Db()
# 3km distace radious for a match
cached_place_name = db.get_location_name(lat, lon, 3000)
if(cached_place_name is not None):
return cached_place_name
lookup_place_name = None
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geolocation_info = reverse_lookup(lat, lon)
if(geolocation_info is not None):
if('address' in geolocation_info):
address = geolocation_info['address']
if('city' in address):
lookup_place_name = address['city']
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elif('state' in address):
lookup_place_name = address['state']
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elif('country' in address):
lookup_place_name = address['country']
if(lookup_place_name is not None):
db.add_location(lat, lon, lookup_place_name)
# TODO: Maybe this should only be done on exit and not for every write.
db.update_location_db()
return lookup_place_name
def reverse_lookup(lat, lon):
if(lat is None or lon is None):
return None
key = get_key()
try:
params = {'format': 'json', 'key': key, 'lat': lat, 'lon': lon}
headers = {"Accept-Language": constants.accepted_language}
r = requests.get(
'http://open.mapquestapi.com/nominatim/v1/reverse.php?%s' %
urllib.urlencode(params), headers=headers
)
return r.json()
except requests.exceptions.RequestException as e:
if(constants.debug is True):
print e
return None
except ValueError as e:
if(constants.debug is True):
print r.text
print e
return None
def lookup(name):
if(name is None or len(name) == 0):
return None
key = get_key()
try:
params = {'format': 'json', 'key': key, 'location': name}
if(constants.debug is True):
print 'http://open.mapquestapi.com/geocoding/v1/address?%s' % urllib.urlencode(params) # noqa
r = requests.get(
'http://open.mapquestapi.com/geocoding/v1/address?%s' %
urllib.urlencode(params)
)
return r.json()
except requests.exceptions.RequestException as e:
if(constants.debug is True):
print e
return None
except ValueError as e:
if(constants.debug is True):
print r.text
print e
return None